4 // Effect is the base class for every effect. It basically represents a single
5 // GLSL function, with an optional set of user-settable parameters.
7 // A note on naming: Since all effects run in the same GLSL namespace,
8 // you can't use any name you want for global variables (e.g. uniforms).
9 // The framework assigns a prefix to you which will be unique for each
10 // effect instance; use the macro PREFIX() around your identifiers to
11 // automatically prepend that prefix.
27 // Can alias on a float[2].
29 Point2D(float x, float y)
35 // Can alias on a float[3].
37 RGBTriplet(float r, float g, float b)
43 // Can alias on a float[4].
45 RGBATriplet(float r, float g, float b, float a)
46 : r(r), g(g), b(b), a(a) {}
51 // Convenience functions that deal with prepending the prefix.
52 GLint get_uniform_location(GLuint glsl_program_num, const std::string &prefix, const std::string &key);
53 void set_uniform_int(GLuint glsl_program_num, const std::string &prefix, const std::string &key, int value);
54 void set_uniform_float(GLuint glsl_program_num, const std::string &prefix, const std::string &key, float value);
55 void set_uniform_vec2(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values);
56 void set_uniform_vec3(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values);
57 void set_uniform_vec4(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values);
58 void set_uniform_vec4_array(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const float *values, size_t num_values);
59 void set_uniform_mat3(GLuint glsl_program_num, const std::string &prefix, const std::string &key, const Eigen::Matrix3d &matrix);
65 // An identifier for this type of effect, mostly used for debug output
66 // (but some special names, like "ColorspaceConversionEffect", holds special
67 // meaning). Same as the class name is fine.
68 virtual std::string effect_type_id() const = 0;
70 // Whether this effects expects its input (and output) to be in
71 // linear gamma, ie. without an applied gamma curve. Most effects
72 // will want this, although the ones that never actually look at
73 // the pixels, e.g. mirror, won't need to care, and can set this
74 // to false. If so, the input gamma will be undefined.
76 // Also see the note on needs_texture_bounce(), below.
77 virtual bool needs_linear_light() const { return true; }
79 // Whether this effect expects its input to be in the sRGB
80 // color space, ie. use the sRGB/Rec. 709 RGB primaries.
81 // (If not, it would typically come in as some slightly different
82 // set of RGB primaries; you would currently not get YCbCr
83 // or something similar).
85 // Again, most effects will want this, but you can set it to false
86 // if you process each channel independently, equally _and_
87 // in a linear fashion.
88 virtual bool needs_srgb_primaries() const { return true; }
90 // How this effect handles alpha, ie. what it outputs in its
91 // alpha channel. The choices are basically blank (alpha is always 1.0),
92 // premultiplied and postmultiplied.
94 // Premultiplied alpha is when the alpha value has been be multiplied
95 // into the three color components, so e.g. 100% red at 50% alpha
96 // would be (0.5, 0.0, 0.0, 0.5) instead of (1.0, 0.0, 0.0, 0.5)
97 // as it is stored in most image formats (postmultiplied alpha).
98 // The multiplication is taken to have happened in linear light.
99 // This is the most natural format for processing, and the default in
100 // most of Movit (just like linear light is).
102 // If you set INPUT_AND_OUTPUT_ALPHA_PREMULTIPLIED, all of your inputs
103 // (if any) are guaranteed to also be in premultiplied alpha.
104 // Otherwise, you can get postmultiplied or premultiplied alpha;
105 // you won't know. If you have multiple inputs, you will get the same
106 // (pre- or postmultiplied) for all inputs, although most likely,
107 // you will want to combine them in a premultiplied fashion anyway
110 // Always outputs blank alpha (ie. alpha=1.0). Only appropriate
111 // for inputs that do not output an alpha channel.
112 // Blank alpha is special in that it can be treated as both
113 // pre- and postmultiplied.
116 // Always outputs premultiplied alpha. As noted above,
117 // you will then also get all inputs in premultiplied alpha.
118 // If you set this, you should also set needs_linear_light().
119 INPUT_AND_OUTPUT_ALPHA_PREMULTIPLIED,
121 // Always outputs postmultiplied alpha. Only appropriate for inputs.
122 OUTPUT_ALPHA_POSTMULTIPLIED,
124 // Keeps the type of alpha unchanged from input to output.
125 // Usually appropriate if you process all color channels
126 // in a linear fashion, and do not change alpha.
128 // Does not make sense for inputs.
129 DONT_CARE_ALPHA_TYPE,
131 virtual AlphaHandling alpha_handling() const { return INPUT_AND_OUTPUT_ALPHA_PREMULTIPLIED; }
133 // Whether this effect expects its input to come directly from
134 // a texture. If this is true, the framework will not chain the
135 // input from other effects, but will store the results of the
136 // chain to a temporary (RGBA fp16) texture and let this effect
137 // sample directly from that.
139 // There are two good reasons why you might want to set this:
141 // 1. You are sampling more than once from the input,
142 // in which case computing all the previous steps might
143 // be more expensive than going to a memory intermediate.
144 // 2. You rely on previous effects, possibly including gamma
145 // expansion, to happen pre-filtering instead of post-filtering.
146 // (This is only relevant if you actually need the filtering; if
147 // you sample 1:1 between pixels and texels, it makes no difference.)
149 // Note that in some cases, you might get post-filtered gamma expansion
150 // even when setting this option. More specifically, if you are the
151 // first effect in the chain, and the GPU is doing sRGB gamma
152 // expansion, it is undefined (from OpenGL's side) whether expansion
153 // happens pre- or post-filtering. For most uses, however,
154 // either will be fine.
155 virtual bool needs_texture_bounce() const { return false; }
157 // Whether this effect expects mipmaps or not. If you set this to
158 // true, you will be sampling with bilinear filtering; if not,
159 // you could be sampling with simple linear filtering and no mipmaps
160 // (although there is no guarantee; if a different effect in the chain
161 // needs mipmaps, you will also get them).
162 virtual bool needs_mipmaps() const { return false; }
164 // Whether this effect wants to output to a different size than
165 // its input(s) (see inform_input_size(), below). If you set this to
166 // true, the output will be bounced to a texture (similarly to if the
167 // next effect set needs_texture_bounce()).
168 virtual bool changes_output_size() const { return false; }
170 // If changes_output_size() is true, you must implement this to tell
171 // the framework what output size you want.
173 // Note that it is explicitly allowed to change width and height
174 // from frame to frame; EffectChain will reallocate textures as needed.
175 virtual void get_output_size(unsigned *width, unsigned *height) const {
179 // Tells the effect the resolution of each of its input.
180 // This will be called every frame, and always before get_output_size(),
181 // so you can change your output size based on the input if so desired.
183 // Note that in some cases, an input might not have a single well-defined
184 // resolution (for instance if you fade between two inputs with
185 // different resolutions). In this case, you will get width=0 and height=0
186 // for that input. If you cannot handle that, you will need to set
187 // needs_texture_bounce() to true, which will force a render to a single
188 // given resolution before you get the input.
189 virtual void inform_input_size(unsigned input_num, unsigned width, unsigned height) {}
191 // How many inputs this effect will take (a fixed number).
192 // If you have only one input, it will be called INPUT() in GLSL;
193 // if you have several, they will be INPUT1(), INPUT2(), and so on.
194 virtual unsigned num_inputs() const { return 1; }
196 // Let the effect rewrite the effect chain as it sees fit.
197 // Most effects won't need to do this, but this is very useful
198 // if you have an effect that consists of multiple sub-effects
199 // (for instance, two passes). The effect is given to its own
200 // pointer, and it can add new ones (by using add_node()
201 // and connect_node()) as it sees fit. This is called at
202 // EffectChain::finalize() time, when the entire graph is known,
203 // in the order that the effects were originally added.
205 // Note that if the effect wants to take itself entirely out
206 // of the chain, it must set “disabled” to true and then disconnect
207 // itself from all other effects.
208 virtual void rewrite_graph(EffectChain *graph, Node *self) {}
210 // Outputs one GLSL uniform declaration for each registered parameter
211 // (see below), with the right prefix prepended to each uniform name.
212 // If you do not want this behavior, you can override this function.
213 virtual std::string output_convenience_uniforms() const;
215 // Returns the GLSL fragment shader string for this effect.
216 virtual std::string output_fragment_shader() = 0;
218 // Set all OpenGL state that this effect needs before rendering.
219 // The default implementation sets one uniform per registered parameter,
220 // but no other state.
222 // <sampler_num> is the first free texture sampler. If you want to use
223 // textures, you can bind a texture to GL_TEXTURE0 + <sampler_num>,
224 // and then increment the number (so that the next effect in the chain
225 // will use a different sampler).
226 virtual void set_gl_state(GLuint glsl_program_num, const std::string& prefix, unsigned *sampler_num);
228 // If you set any special OpenGL state in set_gl_state(), you can clear it
229 // after rendering here. The default implementation does nothing.
230 virtual void clear_gl_state();
232 // Set a parameter; intended to be called from user code.
233 // Neither of these take ownership of the pointer.
234 virtual bool set_int(const std::string&, int value) MUST_CHECK_RESULT;
235 virtual bool set_float(const std::string &key, float value) MUST_CHECK_RESULT;
236 virtual bool set_vec2(const std::string &key, const float *values) MUST_CHECK_RESULT;
237 virtual bool set_vec3(const std::string &key, const float *values) MUST_CHECK_RESULT;
238 virtual bool set_vec4(const std::string &key, const float *values) MUST_CHECK_RESULT;
241 // Register a parameter. Whenever set_*() is called with the same key,
242 // it will update the value in the given pointer (typically a pointer
243 // to some private member variable in your effect).
245 // Neither of these take ownership of the pointer.
247 // int is special since GLSL pre-1.30 doesn't have integer uniforms.
248 // Thus, ints that you register will _not_ be converted to GLSL uniforms.
249 void register_int(const std::string &key, int *value);
251 // These correspond directly to float/vec2/vec3/vec4 in GLSL.
252 void register_float(const std::string &key, float *value);
253 void register_vec2(const std::string &key, float *values);
254 void register_vec3(const std::string &key, float *values);
255 void register_vec4(const std::string &key, float *values);
257 // This will register a 1D texture, which will be bound to a sampler
258 // when your GLSL code runs (so it corresponds 1:1 to a sampler2D uniform
261 // Note that if you change the contents of <values>, you will need to
262 // call invalidate_1d_texture() to have the picture re-uploaded on the
263 // next frame. This is in contrast to all the other parameters, which are
264 // set anew every frame.
265 void register_1d_texture(const std::string &key, float *values, size_t size);
266 void invalidate_1d_texture(const std::string &key);
276 std::map<std::string, int *> params_int;
277 std::map<std::string, float *> params_float;
278 std::map<std::string, float *> params_vec2;
279 std::map<std::string, float *> params_vec3;
280 std::map<std::string, float *> params_vec4;
281 std::map<std::string, Texture1D> params_tex_1d;
284 #endif // !defined(_EFFECT_H)